In a direct fuel injection type engine, fuel is directly injected in each combustion chamber of the engine. As a fuel injection valve (hereinbelow, also referred to as an “injector”) used for a gasoline-fuel direct-injection type engine, a fuel injection valve having a nozzle with a swirler is known. This fuel injection valve has an injection orifice for injecting fuel, a movable valve element for opening and closing said injection orifice by the motion of its axial direction, and a fuel swirling means for giving swirling force at the upper stream of said injection orifice to fuel passing through a fuel passage. The fuel swirling means, referred to as a swirler, gives a swirling force on the basis of the central axis of the injection orifice to fuel.
In prior arts of the fuel injection valve having nozzle with swirler, the following injection valves are proposed to make a fuel spray deflect in the predetermined direction or obtain a required the spray shape. For example, in one of them, the injection orifice is slanted with a predetermined deflection angle in relation to the central axis of the valve element (valve body), as described in Japanese Patent Laid-Open No. H 11(1999)-159421. In another of them, the outlet of the injection orifice is formed in the shape of a step namely difference in level, as described in Japanese Patent Laid-Open No. 2000-329036. The injection orifice having the step is formed in the direction according with the central axis of the valve element (the central axis of the injection valve body and the nozzle body).
As combustion forms of the direct fuel injection type engine, a stratified combustion form and a homogeneous combustion form are well known. The stratified combustion is a combustion style that a flammable air-fuel mixture layer having a ratio close to a theoretical air-fuel ratio is formed around an ignition plug for combustion. As the stratified combustion is utilized especially upon a lean burn mode which the air-fuel ratio is larger than the theoretical air-fuel ratio and mainly used upon the lower load driving and idle operations, low fuel consumption of the engine is attained. The homogeneous combustion is a combustion style that the air-fuel mixture in the combustion chamber is entirely made to be homogenized with the theoretical air-fuel ratio. The homogeneous combustion is suitable to middle- and high-load driving.
Optimized settings of the direction, the shape, the length of penetration and existence/absence of the lead spray etc. of the fuel spray injected in a cylinder by the fuel injection valve, is difference in dependence each type of internal combustion engine, namely in dependence of combustion styles, shapes of combustion chambers, relative positional relations between ignition plug and fuel injection valve, and the like. The above-mentioned penetration length means the reachable distance of the fuel spray injected from the injection valve. The lead spray means the maximum length spray area in the fuel spray.
In the conventional fuel injection valves, they have merely the deflection angle of injection orifice or the step of the outlet of the injection orifice. Accordingly, the optimization of the fuel spray direction, the spray shape, the penetration length, existence/absence of the lead spray in correspondence with each type of internal combustion engines is limited, and the optimized setting cannot be sufficiently made, in viewpoints of combustion performance, fuel economical efficiency and exhaust gas performance,.
In the respective viewpoints of combustion performance, fuel economical efficiency and exhaust gas performance, the present invention provides a fuel injection valve having excellent injection performance and a direct-fuel injection type engine with the fuel injection valve. That is, the present invention is to realize the high freedom in setting of the direction fuel spray, the spray shape, the penetration length, the lead spray etc. of the fuel spray, and to obtain the optimized fuel spray in correspondence with each type of internal combustion engines.